Bump version number to 0.4.0-pre.0 and add note to README

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rand"
-version = "0.3.19"
+version = "0.4.0-pre.0"
 authors = ["The Rust Project Developers"]
 license = "MIT/Apache-2.0"
 readme = "README.md"

README.md

@@ -23,6 +23,13 @@ and this to your crate root:
 extern crate rand;
 ```
 
+### Unstable channel
+
+The 'master' branch tracks development code while the '0.3' branch tracks the
+latest stable release. New features are currently being released in an "unstable
+channel"; if you wish to opt-in to the latest releases (expect some breaking
+changes) specify `rand = "0.4.0-pre.0"`.
+
 ## Examples
 
 There is built-in support for a random number generator (RNG) associated with each thread stored in thread-local storage. This RNG can be accessed via thread_rng, or used implicitly via random. This RNG is normally randomly seeded from an operating-system source of randomness, e.g. /dev/urandom on Unix systems, and will automatically reseed itself from this source after generating 32 KiB of random data.

src/lib.rs

@@ -1021,7 +1021,7 @@ pub fn random<T: Rand>() -> T {
 }
 
 #[inline(always)]
-#[deprecated(since="0.3.18", note="renamed to seq::sample_iter")]
+#[deprecated(since="0.4.0", note="renamed to seq::sample_iter")]
 /// DEPRECATED: use `seq::sample_iter` instead.
 ///
 /// Randomly sample up to `amount` elements from a finite iterator.